Hi!

Tomorrow, on 23rd of January at 18:35 MSK Codeforces Round #340 (Div. 2) will take place. It's my first round, hope you enjoy the problems.

Thanks to GlebsHP for his help in preparing the problems, Delinur for translations of statements and MikeMirzayanov for Codeforces and Polygon.

Good luck!

UPD Scoring 500-1000-1250-1750-2750

UPD Editorial

UPD Congrats to winners!

Div. 2

1. AReesha

2. kpw29

3. I_love_Varechka

4. zhaoxinyi

5. thatday

Div. 1

1. anta

2. dreamoon_love_AA

3. uwi

4. Um_nik

5. I_love_Tanya_Romanova

Warning! The dates of the Winter Computer Camp have shifted one day ahead!

Update: due to technical difficulties, English speaking participants couldn't participate in the fourth selection round. Due to this, the Organizing Committee decided to carry out another selection round on 14 February at 15:00 Moscow Time. Everyone is invited to participate in this round, but preference will be given to foreign participants preeminently.

From 25 February to 5 March 2016, the Moscow Insitute for Physics and Technology will host the seventh Winter Computer Camp 2016 (WCC-2016) in the city of Dolgoprudny. Students of upper grades are welcome to participate.

The program of the camp includes::

• Daily studying contests: preparation to the finals of the Open Olympiad, finals of national programming Olympiads.

• Olympiads in programming and mathematics.

• Lectures by workers of base organizations of FIHT about actual tasks in the IT Industry.

• Lectures by professional scientists on combinatorial mathematics.

• Sports and intellectual games.

How to get to the school:

1. Fill in the registration form.
2. Participate in the online selection rounds for the camp. Pay attention that the selection is conducted thoroughly in compliance with the results of the selection rounds.

Online selection rounds*:

• 27.12.2015 15:00 (UTC+03) — first round,

• 17.01.2016 15:00 (UTC+03) — second round,

• 24.01.2016 15:00 (UTC+03) — third round,

• 07.02.2016 10:00 (UTC+03) — fourth round

**the dates and time of the rounds can change, follow the information on [our website].(http://it-edu.mipt.ru/en/zksh2016).

Cost of participation:

• Free participation is guaranteed to the winners and prizers of the final stage of the All-Russian Olympiad for School Students (or CIS Olympiads) in Informatics and Mathematics.

• 9900 for winners and awardees of the ALl-Russian Team Olympiad for School Students in Programming and the Open Olympiad for School Students in Programming.

• 15900 rubles for participants of the final stage of national Olympiads for school students in informatics and mathematics

• 28900 rubles for other participants.

For any occuring questions, leave messages on the organizing committee email: [email protected]

The head of programming committee of Winter Computer Camp 2016 is Endagorion.

The Winter Computer Camp is traditionally unique for its line-up of participants: Dolgoprudny hosts large numbers of capable students who already have achievements in All-Russian and National Olympiads of different countries. Preparation of contests is performed by young teachers, professors and students — prize-winners of All-Russian Olympiads for School Students and ACM ICPC student tournaments. Therefore, participation in the WCC-2016 serves as a "final rehearsal" before the Finals of the Open Olympiad and the All-Russian Olympiad in Informatics.

Hello, Codeforces!

Educational Codeforces Round 6 will take place on 21 January 2016 at 18:00 MSK for the first and second divisions. You can read about educational rounds here and here.

<Your Ad Could Be Here>

The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

If you have ideas for some problems or maybe already prepared problems that you can't use in rounds or official competitions, you can write to me.

</Your Ad Could Be Here>

Thanks a lot to Aleksa Plavsic allllekssssa who suggested several problems, two of them you will see on the round (the problems D and F). Also thanks to Bayram Berdiyev bayram, Allanur Shiriyev Allanur, Bekmyrat Atayev Bekmyrat.A. They are together suggested five problems, two of them you will see on the round (the problems B and E).

As usual the round was prepared by me, Edvard Davtyan. Thanks a lot to MikeMirzayanov we invented the problems A and C together. Also thanks to Maria Belova Delinur who will check English statements and Aleksa Plavsic allllekssssa who help me with problem testing and have constantly been in touch.

The first problem is pretty simple, so I'm waiting fast accepteds from you. The last problem is pretty difficult, so respect to all particiants who will solve it. I hope you will enjoy the problems!

Good luck and have fun!

UPD 1: I forgot to thank all other users who already sent me the ideas for the problems. I'll try to give that problems to the next rounds.

UPD 2: The main part of the contest is finished. The phase of hacks is started.

UPD 3: The editorial is ready.

UPD 4: The round is over, the results is final.

Teams advancing to 2016 WF Phuket in Asia have been announced recently. This announcement is undisputedly tantamount to a death sentence for me. I am the one waiting anxiously, refresh Dr. Hwang's blog everyday. But it seems that for years, our training was meaningless.

I think many of us dedicate our passion to programming contests because we see them transparent, fair and without any corruption. And I also believe that as contestants, what we should do is only focus on the practice. And I thought those political business should never come to bother me one day. But sadly, it is my team who is going to become one of the sacrifices of a succession of the dissension.

What happened so far

The quarrel between the Asia director and the local community is a long story to tell. But it has never been as serious as it was in the past season. Now reflecting on this, I know on the surface everything is going okay, but I still feel something wrong. The number of slots is decreasing, as well as the power of those multifarious bonus are rising. So the feeling of the unfairness multiplied. According to this article, before the last day, you do not know the exact X or Y in his algorithm. That means, you can always put any number to these parameters after the contest. And the way he decided to put in those variables, which was quite arbitrary and dictatorial. I am afraid those parameters were used to suppress opponents and those who are close to Dr. Hwang will be easy to pass. Now can it be right, to reject a team on the relationship between the authority? But it is exactly what we do, and now it is almost a open secret for us. If you guys have any opposition, you are directly set yourself to the hard mode. In quicksort, there is a strategy called “killer adversary”, I think that is exactly our situation. In fact, last year in China, the contest divided into 2 events, one called ICPC and another is called CCPC. The CCPC event is simultaneous with Changchun site. And some of the school last year was united to refuse to take part in Changchun Site in order to against the overladen bonus, according to the board, we could see there are lots of strong teams seems didn’t come and take part in the Changchun site. But despite of this, Changchun site still get 1 more slot than other sites, and some site has 3 slots while some site is only 1 slot barely. Is that fair? I don’t think so. Last year, I thought staying in the top 6 could have a chance to enter final… This year, I thought staying in the top 2 must have a chance to enter final. As far as I know, there is no team in our region in history which get 2nd place but cannot go to final. And the logic is the same as what he has done on the Chennai flood. Initially a rule was brought out to reduce the number of slots from Chennai to 1. It was later decided to award an extra slot to Chennai. But it turned out, this extra slot was actually the bonus slot that was going to be given to Amritapuri (as it had proposed to host the world finals in future, smell some sense of Stockholm syndrome?). The net effect is, the number of teams from India is reduced due to postponement rule announced so hastily after the Chennai regional was postponed. This awarding of the extra slot to Chennai is just a sleight of hand designed to look like it is fair.

My wish

Well, don’t get me wrong. I am not against the rule this year, I am against the way the rule has been made. The problem with this system, is that it’s this sort of long, slow expansion in personal power. If you don't make a sound this time, things may become more and more dangerous in the future. One of my spiritual idol Aaron Swartz once argued that it was sometimes necessary to break the rules that required obedience to the system in order to avoid systemic evil. So, at my point of view, at least all officials concerned should be consulted. There should be some discussion before taking any decision. The voting should be transparent. The slot calculation is needlessly complicated and could be much simplified. There could be bonus slots but shouldn’t affect the acknowledged game rules. There should be no parameters remain to be determined after the contest. I know in the early day in the ICPC history, Dr. Hwang had done great contribution to bring this event for us. But as times alter, today, the power is overwhelming, and he is stand on the opposite of the sport spirit, the way in which Dr. Hwang makes decision should be questioned. What he has done this time is just to make an example out of us, to use this case for deterrence. So that next time we are submitted to his power. And if we could not do something that take a fair environment back, the reputation of the contest in the sub-region will be badly influenced. Do we really willing to see there are 5 CCPC together with 5 ICPC in the coming season? Do we really need this privilege to keep the health and vitality? I am afraid our students will be seriously exhausted on this issue and the community will appear to diverge further.

Update

Thanks everyone!

Dr. Hwang has just replied to me that he will try after one week for an additional participation slot for Asia. But still said nothing about the X+Y scheme. Looking for the further reaction. The chance is slim. But no matter what outcome will be, I have already felt the warmth of the community!

Everyone on this site heard about problem preparing tool, maintained by MikeMirzayanov called polygon.

It have a lot of advantages, like automatic checks of everything you can imagine. But also, it have several very annoying things. The main one for me is necessity of synchronizing solutions and generators files by hand, between polygon and your local copy. So I had written a tool, which can do it.

Tool is published on github, with instructions how to install it. You are welcome with any new features/suggestions (I'm not knowing python very well, to be honest).

Known problems:

• Not tested good enough, probably buggy
• Installation script working strange. Anyone knowing python better? Any better ways to distribute?
• Sometimes lost of session is not detected and script fails with strange non-readable errors. relogin helps
• Parsing html pages can be not stable enough with changing polygon. Waiting for better api from MikeMirzayanov and codeforces team.

Hi all!

In two days, at 19:35 MSK Codeforces Round #339 (Div. 1 & Div. 2) will take place. This is an unusual round since we — the problemsetters — are highschool students who participate in the programming training group at high school #179. This round is our first effort and we did our best to make it interesting and bug-free. I invite you all to compete in this round since the problems will be solvable, but even tourist will have to think over some of them. :)

With supervision and control from Mikhail Tikhomirov (Endagorion), the problems were developed by: Egor Chunaev (ch_egor), Vasily Alferov (platypus179), Dmitry Sayutin (cdkrot), Timofey Gutor (Tigutor), Maria Fedorkina (crossopt). Mikhail Sorokin (themikemikovi4) and Sergey Aleikin (Derrior) contributed their problem ideas.

We thank Gleb Evstropov (GlebsHP) for his help in preparing the contest, Maria Belova (Delinur) for translating the statements in English, AlexFetisov and winger for testing, and, of course, MikeMirzayanov for unique CodeForces and Polygon systems.

Round will have standard Codeforces rules, with pretests at first, and final tests afterwards. Take care to account for all possible cases.

Best of luck to everyone!

UPD Points for problems are

Div 2. 500-1000-1750-2250-2250, Div 1. 750-1250-1250-2000-2500

UPD Congratulations winners! standings

Div1:

1. TankEngineer

2. KAN

3. Petr

4. Um_nik

5. snuke

6. matthew99

7. jcvb

8. superpear

9. pashka

10. fsouza

Div2:

1. mingaleg

2. Ronnoc

3. BoQiR

4. maks1906

5. zloyplace35

6. huansuz1

7. 2016

8. Danlark

9. MrPapaya

10. bohuss

UPD Editorial

Hi, Codeforces!

Happy New Year! Holidays and 2015 year have passed and year 2016 is ahead. I wish you good luck in programming competitions and achieving all of your goals this year.

Educational Codeforces Round 5 will take place on 11 January 2016 at 18:00 MSK for the first and second divisions. You can read about educational rounds here and here.

<A year has passed, but paragraph remains unchanged.>

The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

</A year has passed, but paragraph remains unchanged.>

Thanks a lot to Grigory Reznikow vintage_Vlad_Makeev who prepared a good problem (the problem F in ER 5). You can send to me some ideas of problems or maybe already prepared problems that you can't use in rounds or official competitions.

As usual the round was prepared by me, Edvard Davtyan. Thanks a lot to MikeMirzayanov for helping to invent the problems. Also thanks in advance to Maria Belova Delinur who will check English statements.

I think the problems is not difficult (except maybe for problem F). I hope you will enjoy the problems and solve all of them!

Good luck and have fun!

UPD 1: Coding phase is finished. You can hack other solutions for 24 hours.

UPD 2: The editorial is ready.

UPD 3: During the phase of hacks we found the following: the same solutions on Python2 and Python3 works differently on different large tests. For example, some of Python3 solutions works very slow on tests with only zeros, but Python2 works very slow on tests with nines. Some of solutions works in around one second so we decided to increase the time limit for the problem A to 2 seconds. All the solutions will be rejudged soon on the complete testset.

UPD 4: The round is over. All solutions will be rejudged soon on the complete testset (includes the hacks).

Facebook Hacker Cup 2016 is starting soon. Don't miss the qualification round, which starts at midnight UTC and lasts for 3 days. To advance, you will need to solve at least one problem.

This year's finals will be in London, so this is another chance for those who missed GCJ finals in 2013.

You can enter the round using this link, but you need to log into Facebook first.

Greetings!

Codeforces Round #338 (Div. 2) will be held tomorrow. Note that round starts at the unusual time! This round was made by Maxim Vinnichenko(maxkvant), and me, Alexander Zoykin. It is our first round and we hope that everything will be OK. Thanks to GlebsHP for the great help in preparing the contest, Bobrosoft for being more than tester, Delinur for translating the statements into English, and MikeMirzayanov for the great Polygon and Codeforces systems.

score distribution 500 — 1250 — 1750 — 2000 — 2500

Good luck!

upd Congratulations to winners!

div 2:

zhangzj_is_our_sun

marcorezieho

Claris

ucfpt

Tomer.Adar

div 1:

I_love_Tanya_Romanova

ngfam_kongu

sd0061

pavel.savchenkov

ershov.stanislav

Editorial

Hello!

Here are some statistics about 2015. I'm glad to see our growth. Frankly, each year I'm afraid to see that we stop to grow, but each year I see 20-50% growth! Thank you for your interest :-)

In addition, I have written before about progress in the development and championships and rounds with partner companies in 2015. If you have not read, please read.

Here are the funny pictures with the statistics:

Growth of registerations. This year we overcame 300K users!